Bottom pour ladles used in pouring molten metals are customarily fabricated from or lined with refractory, i.e., nonfusible, material, capable of withstanding the enormous heats involved in molten metal processing.
Similarly, the stopper elements or plug which controls the flow of molten metal is also comprised of a non-fusible material. However, the stopper rod, generally mounted within the stopper plug, is metal and therefore subject to warpage, deflection and/or deterioration caused by the heat of the molten metal despite the protective sheathing of refractory material in which it is mounted. This stopper rod damage often leads to the misalignment of the stopper plug and, so, spillage.
The problems of stopper plug misalignment, stopper rod deterioration and of spillage have been dealt with through attempted improvements in the stopper plug and in the stopper plug and rod assembly which were designed to achieve better sheathing of the stopper rod by the plug. Examples of such prior art attempts are disclosed by U.S. Pat. No. 1,290,614 to McFarland; U.S. Pat. No. 2,195,791 to Slick; U.S. Pat. No. 3,103,720 to Roberts; and U.S. Pat. No. 3,044,132 to Murton.
There are, however, still disadvantages and drawbacks inherent in even the so-called improved embodiments of conventional stopper plug and stopper rod assemblies. Specifically, sectioned stopper plugs are susceptible to fracture during use and the stopper rods continue to be vulnerable to warpage and deterioration. Moreover, such prior art devices are, as a rule, not easily accessible for reworking. A further and serious drawback commonly experienced with conventional stopper plugs is the problem of spillage caused by stopper rod warpage and the misalignment of the stopper plug with the pouring nozzle.
The present invention serves to correct and ameliorate the difficulties experienced in existing stopper rod assemblies by providing a uniquely designed stopper head which will eliminate accidental spillage. Moreover, the novel stopper plug allows for positive on-off control and prevents the formation of skulls or pans.
A further advantage of the novel stopper plug is inherent in its construction, which provides a refractory cemented, bifurcated stopper head with a large sealing surface, resistant to fracture and allowing easy access to the stopper rod for reworking and strengthening when necessary.